[This piece is an excerpt from the first chapter of Sandra’s new book, Replenish: The Virtuous Cycle of Water and Prosperity, released this week by Island Press.]

As I wound my way up Poudre Canyon in northern Colorado, the river flowed toward the plains below, glistening in the midday sun. It ran easy and low, as it normally does as the autumn approaches, with the snowmelt long gone. I was struck by the canyon’s beauty, but also by the blackened soils and charred tree trunks that marred the steep mountains all around. They were legacies, I realized, of the High Park Fire that had burned more than 135 square miles (350 square kilometers) of forest during the previous year’s drought.

It was September 7, 2013, and my family and I were heading to my niece’s wedding. Tara and Eric had chosen a spectacular place for their nuptials—Sky Ranch, a high mountain camp not far from the eastern fringe of Rocky Mountain National Park. As we escorted my elderly parents down the rocky path to their seats, I noticed threatening clouds moving in. They darkened as the preacher delivered his homily. Please cut it short and marry them, I thought to myself, before we all get drenched.

The rains held off just long enough. But that day’s brief shower was a prelude to a deluge of biblical proportions that began four days later. A storm system stalled over the Front Range and in less than a week dumped nearly a year’s worth of precipitation in some areas. The Poudre— short for Cache la Poudre—flooded bigger than it had since 1930. The torrential rains washed dead tree trunks down the hillsides into the raging river below. One canyon resident wrote that the blackened logs “looked like Tinker Toys amid the river’s mad rush.”

As air warms, it expands, which allows it to hold more moisture. This, in turn, increases evaporation and precipitation, which generally makes dry areas drier and wet areas wetter. If disasters related to droughts, floods, and other extreme weather seem more common globally, it’s because they are: according to a United Nations study, between 2005 and 2014, an average of 335 weather-related disasters occurred per year, nearly twice the level recorded from 1985 to 1995.So often these days water seems to be nowhere and everywhere all at once. The wild weather of 2015 became almost legendary, even before the year was over. With raging floods in Latin America, the US Midwest, and the United Kingdom, and withering droughts in eastern and southern Africa, most of California and southeastern Brazil, terms such as anomalous, historic, and epic dominated the weather lexicon. US scientists determined that during one rare October rainstorm 17 streams in the US state of South Carolina broke records for peak flow. According to the United Nations, two years of drought left nearly 1 million African children suffering from acute malnutrition, and millions more at risk from hunger, water shortages, and disease.

Leaders in business and government are beginning to take notice. More than 90 percent of companies in the S&P Global 100 Index see extreme weather and climate change impacts as current or future risks to their business. At its annual gathering in Davos, Switzerland, in 2016, the World Economic Forum—which counts among its members heads of state, chief executive officers, and civic leaders—declared water crises to be the top global risk to society over the next decade. Next on the list were the failure to mitigate and adapt to climate change, extreme weather events, food crises, and profound social instability.

All five threats are intimately connected to water. Guarding against each requires a new understanding of our relationship to freshwater—and a new way of thinking about how we use, manage, and value it.

For the last two centuries, we have been trading nature’s services for engineering services. Instead of floodplains controlling floods, we built dams and levees to do that work. Instead of healthy watersheds and wetlands cleansing our water supplies, we built filtration plants to provide that service. For the most part, we viewed this substitution of technology for nature as a sign of progress. It gave society more control over water, opened up new lands for development, and spurred economic growth.

But a different view of nature gradually emerged. Natural ecosystems, when healthy and functioning well, are vital to the economy. Watersheds, wetlands, floodplains, and river systems constitute a class of infrastructure doing valuable work, just as dams, canals, and treatment plants do. Assessments led by economist Robert Costanza showed, for example, that the ability of freshwater swamps and river floodplains to store water, mitigate floods, and break down pollutants delivered annual benefits to the economy averaging some $32,000 per hectare ($13,000 per acre; both expressed in 2016 dollars). It was foolish to continue to bulldoze, dike, and drain away these services as if their value were zero.

Lastly, and perhaps most importantly, the changes in weather patterns and water flows that we’re beginning to see as the planet warms call into question the very assumptions that have underpinned our water projects for decades. In 2008, seven top water scientists argued persuasively in the journal Science that “stationarity”—the foundational concept that hydrologic systems vary and fluctuate within a known set of boundaries—is dead. When it comes to water, in other words, the past is no longer a reliable guide to the future.

Decades ago, Albert Einstein reminded us of a fundamental lesson that’s hard to learn: “We can’t solve problems by using the same kind of thinking we used when we created them.” Fortunately, just when it’s crucially needed, a new mind-set about water is taking shape. It’s one that blends engineering, ecology, economics, and related fields into a more holistic approach that recognizes the fundamental value of nature’s services.

Sandra Postel. Photo by Cheryl Zook/National Geographic

This evolving mind-set is already changing the way we manage water. Working with, rather than against, nature, pioneering cities, farmers, businesses, and conservationists are rejuvenating watersheds and floodplains, and replenishing rivers, groundwater, and soils. The result is a smarter way to mitigate flood damages, prepare for droughts, restore habitats, grow food, augment water supplies, and generally strengthen water security.

Investing in a healthier water cycle, it turns out, may be the best insurance policy money can buy in this century of rapid change.

Originally posted at National Geographic.